The plot may be very simple and the jokes fairly obvious, but this warm, snappy British comedy builds like a tango from slow start to entertaining finale. The one-joke premise (fat man dances salsa!) is dispensed fairly early on, letting the cast get on with adding hilariously spiky touches to their characters.

As a boy, dance champ Bruce (Frost) turned his back on salsa after being badly bullied. Now an industrial designer, he's startled to discover a spark with his sexy new American boss Julia (Jones), although he has a rival for her in a ruthlessly womanising colleague (O'Dowd). So when he discovers that Julia likes to salsa, he revisits his old mentor (McShane) to see if he still has any moves. His old partner, his sister Sam (Colman), encourages him to go for it, as do his lonely hearts club pals (Kinnear and Plester).

There isn't much to the plot, and it takes awhile for the characters to come alive. The film's first act is subdued, bringing out the occasional smile when a rare gag hits the target, but as we get to know these people, the situations get funnier. And the jokes get sharper. The entrance of supreme scene-stealer Novak (as an enthusiastic fellow dance student) livens things up significantly, as does the increasingly insane behaviour of O'Dowd, leading to a show-stopping maniacally choreographed car park dance-off.

Frost is perhaps the least likely romantic lead ever, and his relationship with Jones is barely plausible, but we can see a hint of interest between them. And it's especially nice that, once Frost hits the dance floor, the film kicks up another gear by embracing Bruce's dance moves rather than playing them for laughs. This gives the movie a good-natured boost, and it lets Colman shine especially brightly in her big scenes.

So in the end we don't mind the mild lesson-learning or heartwarming sentiment. Not only will the film give hope to those who have abandoned their childhood dreams (or put on some weight), but it makes us want to shake our stuff on the dance floor. And because the drama, romance, comedy and music all build to a crescendo at just the right time, it sends us out of the cinema with a huge smile.